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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // let result = ["1","2","3"].map(function(value,index){
        //     return 'hello'+value;
        // })
        // console.log(result);

        console.log(["1", "2", "3"].map(parseInt)); // 1 NaN NaN
        // 值  索引
        // '1' 0  -> 1
        // '2' 1  -> NaN
        // '3' 2  -> NaN
        // console.log(parseInt('12',0))
    </script>
</body>

</html>